Barcelona sauntered to what appeared to be a regulation 4-0 win over Rayo Vallecano on Saturday night, but below the surface, something remarkable was occurring.For the first time in 317 competitive games - 317! - Barcelona finished the game having had less possession than their opponents. Yes, that's 317.Ever since a 4-1 defeat to Real Madrid at the Santiago Bernabeu in May 2008, the master practitioners of tiki-taka had greedily hogged the ball like the best kid in the school playground.This remarkable spell included the entire reigns of former coaches Pep Guardiola - who did so much to refine Barcelona's possession-based strategy - and Tito Vilanova, as the Madrid defeat over five years ago came under Dutchman Frank Rijkaard.In the intervening games they had come up against quality opposition at home and abroad but, until last night, had never seen their possession stat dip below 50%.Remarkably, it was a small club from a working-class Madrid barrio who ended one of sport's great all-time streaks as Rayo notched up 54% possession against a strong Barca line-up which included Lionel Messi, Xavi, Cesc Fabregas and Neymar.While the locals at Vallecas might have been distracted by the heavy beating dished out to their side - with Pedro claiming a hat-trick - at least this morning they can console themselves with the knowledge that they witnessed a little bit of history being made.And how to explain this aberration? Who knows. Barcelona coach Gerardo Martino was full of praise of Rayo, even after beating them comfortably, and said after the match: “Rayo’s approach was very bold. Aggressive. They had an excellent approach."However, Pitchside Europe suspects the fact that Barcelona were missing the brilliant midfield holder Sergio Busquets, and had the rather erratic Alex Song to replace him, explains why the Catalans were unable to exercise their usual control over the game.